Smoking and the risk of prostate cancer in the European Prospective Investigation into Cancer and Nutrition

No association between MTHFR gene C677T/A1298C polymorphisms, serum folate, vitamin B12, homocysteine levels, and prostate cancer in an Algerian population

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate and homocysteine metabolism, which are necessary for DNA methylation and nucleotide synthesis. Genetic polymorphisms that reduce MTHFR activity have been linked to several diseases, including prostate cancer. In this study, we aimed to investigate whether MTHFR polymorphisms, along with serum levels of folate, vitamin B12, and homocysteine, are associated with prostate cancer risk in the Algerian population.

METHODS

A total of 106 Algerian men with newly diagnosed prostate cancer and 125 healthy controls were included in this case-control study. The MTHFR C677T and A1298C polymorphisms were analyzed using PCR/RFLP and Real-Time PCR TaqMan® assays, respectively. Serum levels of folate, total homocysteine, and vitamin B12 were measured using an automatic biochemistry analyzer.

RESULTS

We found no significant differences in the genotype frequency of A1298C and C677T between prostate cancer patients and controls. Moreover, serum levels of folate, total homocysteine, and vitamin B12 were not significantly associated with prostate cancer risk (p > 0.05). However, age and family history were identified as significant risk factors (OR = 1.178, p = 0.00 and OR = 10.03, p = 0.007, respectively).

CONCLUSION

Our study suggests that MTHFR C677T and A1298C, as well as serum levels of folate, total homocysteine, and vitamin B12, are not associated with prostate cancer risk in the Algerian population. However, age and family history are significant risk factors. Further studies with a larger sample size are required to confirm these findings.

Genetic mutations in smoking-associated prostate cancer

OBJECTIVES

Tobacco smoking is known to cause cancers potentially predisposed by genetic risks. We compared the frequency of gene mutations using a next generation sequencing database of smokers and nonsmokers with prostate cancer (PCa) to identify subsets of patients with potential genetic risks.

MATERIALS AND METHODS

Data from the American Association for Cancer Research Project Genomics Evidence Neoplasia Information Exchange (GENIE) registry was analyzed. The GENIE registry contains clinically annotated sequenced tumor samples. We included 1832 men with PCa in our cohort, categorized as smokers and nonsmokers, and compared the frequency of mutations (point mutations, copy number variations, and structural variants) of 47 genes with more than 5% mutation rate between the two categories and correlated with overall survival using logistic regression analysis.

RESULTS

Overall, 1007 (55%) patients were nonsmokers, and 825 (45%) were smokers. The mutation frequency was significantly higher in smokers compared to nonsmokers, 47.6% and 41.3%, respectively (p = 0.02). The median tumor mutational burden was also significantly higher in the samples from smokers (3.59 mut/MB) compared to nonsmokers (1.87 mut/MB) (p < 0.001). Patients with a smoking history had a significantly higher frequency of PREX2, PTEN, AGO2, KMT2C, and a lower frequency of adenomatous polyposis coli (APC) and KMT2A mutations than compared to nonsmokers. The overall mortality rate (28.5% vs. 22.8%) was significantly higher among smokers (p = 0.006). On a multivariate logistic regression analysis, the presence of metastatic disease at the time of diagnosis (OR: 2.26, 95% CI: 1.78-2.89, p < 0.001), smoking history (OR: 1.32, 95% CI: 1.05-1.65, p = 0.02), and higher frequency of PTEN somatic gene mutation (OR: 1.89, 95% CI: 1.46-2.45, p < 0.001) were independent predictors of increased overall mortality among patients with PCa. Patients with PTEN mutation had poorer overall survival compared to men without PTEN mutations: 96.00 (95% CI: 65.36-113.98) and 120.00 (95% CI: 115.05-160.00) months, respectively (p < 0.001) irrespective of smoking history although the G129R PTEN mutation was characteristically detected in smokers.

CONCLUSIONS

PCa patients with a tobacco smoking history demonstrated a significantly higher frequency of somatic genetic mutations. Whereas mutations of PREX2, KMT2C, AGO2, and PTEN genes were higher in smokers, the APC and KMT2A mutations were higher in nonsmokers. The PTEN somatic gene mutation was associated with increased overall mortality among patients with PCa irrespective of smoking history. We found that G129R PTEN mutation known to reduce the PTEN phosphatase activity and K267Rfs*9 a frameshift deletion mutation in the C2 domain of PTEN associated with membrane binding exclusively detected in smokers and nonsmokers, respectively. These findings may be used to further our understanding of PCa associated with smoking.

Risk of urinary tract cancers following arsenic exposure and tobacco smoking: a review

Bladder cancer, prostate cancer, and kidney cancer, due to their high morbidity and mortality rates, result in significant economic and health care costs. Arsenic exposure affects the drinking water of millions of people worldwide. Long-term exposure to arsenic, even in low concentrations, increases the risk of developing various cancers. Smoking is also one of the leading causes of bladder, prostate and kidney cancers. Accordingly, this research reviews the relationship between arsenic exposure and smoking with three kinds of urinary tract cancers (bladder cancer, prostate cancer, and kidney cancer) due to their widespread concern for their negative impact on public health globally. In this review, we have gathered the most current information from scientific databases [PubMed, Scopus, Google Scholar, ISI web of science] regarding the relationship between arsenic exposure and tobacco smoking with the risk of bladder, prostate, and kidney cancer. In several studies, a significant relationship was determined between the incidence and mortality rate of the above-mentioned cancers in humans with arsenic exposure and tobacco smoking. The decrease or cessation of smoking and consumption of arsenic-free water significantly declined the incidence of bladder, prostate, and kidney cancers.

Association of cigarette smoking habits with the risk of prostate cancer: a systematic review and meta-analysis

BACKGROUND

Association of cigarette smoking habits with the risk of prostate cancer is still a matter of debate. This systematic review and meta-analysis aimed to assess the association between cigarette smoking and prostate cancer risk.

METHODS

We conducted a systematic search on PubMed, Embase, Cochrane Library, and Web of Science without language or time restrictions on June 11, 2022. Literature search and study screening were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Prospective cohort studies that assessed the association between cigarette smoking habits and the risk of prostate cancer were included. Quality assessment was conducted using the Newcastle-Ottawa Scale. We used random-effects models to obtain pooled estimates and the corresponding 95% confidence intervals.

RESULTS

A total of 7296 publications were screened, of which 44 cohort studies were identified for qualitative analysis; 39 articles comprising 3 296 398 participants and 130 924 cases were selected for further meta-analysis. Current smoking had a significantly reduced risk of prostate cancer (RR, 0.74; 95% CI, 0.68-0.80; P < 0.001), especially in studies completed in the prostate-specific antigen screening era. Compared to former smokers, current smokers had a significant lower risk of PCa (RR, 0.70; 95% CI, 0.65-0.75; P < 0.001). Ever smoking showed no association with prostate cancer risk in overall analyses (RR, 0.96; 95% CI, 0.93-1.00; P = 0.074), but an increased risk of prostate cancer in the pre-prostate-specific antigen screening era (RR, 1.05; 95% CI, 1.00-1.10; P = 0.046) and a lower risk of prostate cancer in the prostate-specific antigen screening era (RR, 0.95; 95% CI, 0.91-0.99; P = 0.011) were observed. Former smoking did not show any association with the risk of prostate cancer.

CONCLUSIONS

The findings suggest that the lower risk of prostate cancer in smokers can probably be attributed to their poor adherence to cancer screening and the occurrence of deadly smoking-related diseases, and we should take measures to help smokers to be more compliant with early cancer screening and to quit smoking.

TRIAL REGISTRATION

This study was registered on PROSPERO (CRD42022326464).

A Healthy Lifestyle in Men at Increased Genetic Risk for Prostate Cancer

BACKGROUND

Prostate cancer is the most heritable cancer. There is a need to identify possible modifiable factors for men at an increased risk of prostate cancer due to genetic factors.

OBJECTIVE

To examine whether men at an increased genetic risk of prostate cancer can offset their risk of disease or disease progression by adhering to a healthy lifestyle.

DESIGN, SETTING, AND PARTICIPANTS

We prospectively followed 12 411 genotyped men in the Health Professionals Follow-up Study (1993-2019) and the Physicians' Health Study (1983-2010). Genetic risk of prostate cancer was quantified using a polygenic risk score (PRS). A healthy lifestyle was defined by healthy weight, vigorous physical activity, not smoking, and a healthy diet.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Overall and lethal prostate cancer events (metastatic disease/prostate cancer-specific death) were analyzed using time-to-event analyses estimating hazard ratios (HRs) and lifetime risks.

RESULTS AND LIMITATIONS

During 27 yr of follow-up, 3005 overall prostate cancer and 435 lethal prostate cancer events were observed. The PRS enabled risk stratification not only for overall prostate cancer, but also for lethal disease with a four-fold difference between men in the highest and lowest quartiles (HR, 4.32; 95% confidence interval [CI], 3.16-5.89). Among men in the highest PRS quartile, adhering to a healthy lifestyle was associated with a decreased rate of lethal prostate cancer (HR, 0.55; 95% CI, 0.36-0.86) compared with having an unhealthy lifestyle, translating to a lifetime risk of 1.6% (95% CI, 0.8-3.1%) among the healthy and 5.3% (95% CI, 3.6-7.8%) among the unhealthy. Adhering to a healthy lifestyle was not associated with a decreased risk of overall prostate cancer.

CONCLUSIONS

Our findings suggest that a genetic predisposition for prostate cancer is not deterministic for a poor cancer outcome. Maintaining a healthy lifestyle may provide a way to offset the genetic risk of lethal prostate cancer.

PATIENT SUMMARY

This study examined whether the genetic risk of prostate cancer can be attenuated by a healthy lifestyle including a healthy weight, regular exercise, not smoking, and a healthy diet. We observed that adherence to a healthy lifestyle reduced the risk of metastatic disease and prostate cancer death among men at the highest genetic risk. We conclude that men at a high genetic risk of prostate cancer may benefit from adhering to a healthy lifestyle.

Cigarette smoking and prostate cancer: A systematic review and meta-analysis of prospective cohort studies

INTRODUCTION

Cigarette smoking is a well-known cancer-causing behavior and a leading cause of death from cancer. However, according to previously published research and meta-analyses, cigarette smoking has a significant inverse association with prostate cancer incidence. Therefore, this study aims to investigate this association based on updated evidence by conducting a systematic review and meta-analysis.

METHODS

A search for relevant articles was performed in PubMed and Scopus databases to obtain the pooled relative risk (RR) and the corresponding 95% confidence intervals (CIs) for the risk of prostate cancer incidence among smokers compared to non-smokers. Our search was limited to prospective cohort studies.

RESULTS

A total of 17 cohort studies were included in the systematic review. Fifteen studies were included in the meta-analysis and showed that cigarette smoking has an inverse association with prostate cancer incidence with a relative risk of 0.84 (95% CI: 0.78-0.91). From all cohorts included in this systematic review, five studies examined the association between current smokers and the risk of death from prostate cancer. Therefore, a meta-analysis of these cohort studies was performed and showed that current smokers had a 42% higher risk of death from prostate cancer when compared to non-smokers with a relative risk of 1.42 (95% CI: 1.20-1.68).

CONCLUSIONS

Data from observational studies suggest that cigarette smoking has an inverse association with prostate cancer incidence. However, smokers have an increased risk of death from prostate cancer. Important to realize that this lower risk for smokers might be attributed to low prostate cancer screening uptake among smokers, misclassification bias, or selection bias from the included original studies. In summary, our results indicate that the incidence of prostate cancer is lower among smokers. Nevertheless, smokers who develop the disease have a significantly worse prognosis.

Post-diagnostic health behaviour scores in relation to fatal prostate cancer

BACKGROUND

Individual health behaviours have been associated with fatal prostate cancer (PCa). Their combined association with fatal PCa after diagnosis is unknown.

METHODS

This prospective cohort included 4518 men diagnosed with nonmetastatic PCa from the Health Professionals Follow-up Study. Exposures included a three-factor score integrating post-diagnostic fatal PCa risk factors ("2021 PCa Behaviour Score"), six-factor score integrating incident aggressive PCa risk factors ("2015 PCa Behaviour Score"), and two scores integrating recommendations for cancer prevention and survival, respectively. Multivariable Cox models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for fatal PCa.

RESULTS

Over a median 10.2 years, we observed 219 PCa deaths. Each additional point of one of the PCa-specific health behaviour scores (2015 PCa Behaviour Score) was associated with a 19% reduced fatal PCa risk (HR: 0.81, 95%CI: 0.68-0.97). The 2021 PCa Behaviour Score and scores integrating national recommendations were not associated with fatal PCa.

CONCLUSIONS

While a PCa-specific health behaviour score was associated with a reduced risk of fatal PCa, we did not otherwise observe strong evidence of associations between post-diagnostic scores and fatal PCa. Avoiding tobacco, healthy body size, and physical activity may decrease PCa death risk, but further research is needed to inform cancer survivorship recommendations.

Health effects associated with smoking: a Burden of Proof study

As a leading behavioral risk factor for numerous health outcomes, smoking is a major ongoing public health challenge. Although evidence on the health effects of smoking has been widely reported, few attempts have evaluated the dose-response relationship between smoking and a diverse range of health outcomes systematically and comprehensively. In the present study, we re-estimated the dose-response relationships between current smoking and 36 health outcomes by conducting systematic reviews up to 31 May 2022, employing a meta-analytic method that incorporates between-study heterogeneity into estimates of uncertainty. Among the 36 selected outcomes, 8 had strong-to-very-strong evidence of an association with smoking, 21 had weak-to-moderate evidence of association and 7 had no evidence of association. By overcoming many of the limitations of traditional meta-analyses, our approach provides comprehensive, up-to-date and easy-to-use estimates of the evidence on the health effects of smoking. These estimates provide important information for tobacco control advocates, policy makers, researchers, physicians, smokers and the public.

The Impact of Lifestyle on Prostate Cancer: A Road to the Discovery of New Biomarkers

Prostate cancer (PCa) is one of the most common cancers among men, and its incidence has been rising through the years. Several risk factors have been associated with this disease and unhealthy lifestyles and inflammation were appointed as major contributors for PCa development, progression, and severity. Despite the advantages associated with the currently used diagnostic tools [prostate-specific antigen(PSA) serum levels and digital rectal examination (DRE)], the development of effective approaches for PCa diagnosis is still necessary. Finding lifestyle-associated proteins that may predict the development of PCa seems to be a promising strategy to improve PCa diagnosis. In this context, several biomarkers have been identified, including circulating biomarkers (CRP, insulin, C-peptide, TNFα-R2, adiponectin, IL-6, total PSA, free PSA, and p2PSA), urine biomarkers (PCA3, guanidine, phenylacetylglycine, and glycine), proteins expressed in exosomes (afamin, vitamin D-binding protein, and filamin A), and miRNAs expressed in prostate tissue (miRNA-21, miRNA-101, and miRNA-182). In conclusion, exploring the impact of lifestyle and inflammation on PCa development and progression may open doors to the identification of new biomarkers. The discovery of new PCa diagnostic biomarkers should contribute to reduce overdiagnosis and overtreatment.

Smoking and Risk of Prostate Cancer and Prostate Cancer Death: A Pooled Study

BACKGROUND

Prospective and detailed investigations of smoking and prostate cancer (PCa) risk and death are lacking.

OBJECTIVE

To investigate prediagnosis smoking habit (status, intensity, duration, and cessation) as a risk factor, on its own and combined with body mass index (BMI), for PCa incidence and death.

DESIGN, SETTING, AND PARTICIPANTS

We included 351448 men with smoking information from five Swedish cohorts.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We used Cox regression to calculate hazard ratios (HRs) and confidence intervals (CIs) for PCa incidence (n = 24731) and death (n = 4322).

RESULTS AND LIMITATIONS

Smoking was associated with a lower risk of any PCa (HR 0.89, 95% CI 0.86-0.92), which was most pronounced for low-risk PCa (HR 0.74, 95% CI 0.69-0.79) and was restricted to PCa cases diagnosed in the prostate-specific antigen (PSA) era. Smoking was associated with a higher risk of PCa death in the full cohort (HR 1.10, 95% CI 1.02-1.18) and in case-only analysis adjusted for clinical characteristics (HR 1.20, 95% CI 1.11-1.31), which was a consistent finding across case groups (p = 0.8 for heterogeneity). Associations by smoking intensity and, to lesser degree, smoking duration and cessation, supported the associations for smoking status. Smoking in combination with obesity (BMI ≥30 kg/m²) further decreased the risk of low-risk PCa incidence (HR 0.40, 95% CI 0.30-0.53 compared to never smokers with BMI <25 kg/m²) and further increased the risk of PCa death (HR 1.49, 95% CI 1.21-1.84). A limitation of the study is that only a subgroup of men had information on smoking habit around the time of their PCa diagnosis.

CONCLUSIONS

The lower PCa risk for smokers in the PSA era, particularly for low-risk PCa, can probably be attributed to low uptake of PSA testing by smokers. Poor survival for smokers, particularly obese smokers, requires further study to clarify the underlying causes and the preventive potential of smoking intervention for PCa death.

PATIENT SUMMARY

Smokers have a higher risk of dying from prostate cancer, which further increases with obesity.

Inflammation and Prostate Cancer: A Multidisciplinary Approach to Identifying Opportunities for Treatment and Prevention

Prostate cancer is a major cause of disease for men globally. Inflammation, an established hallmark of cancer, is frequently observed in the prostate, though its contribution to prostate cancer risks and outcomes is not fully understood. Prostate cancer is biologically and clinically heterogeneous, and there is now evidence that inflammation and immunological characteristics vary by the genomic and mutational landscape of the tumor. Moreover, it is now recognized that risk factor profiles vary between tumor subgroups, as defined by histopathological and molecular features. Here, we provide a review centered around the relationship between inflammation and prostate cancer, with a consideration of molecular tumor features and a particular focus on the advanced and lethal stages of disease. We summarize findings from epidemiological studies of the etiology and role of inflammation in prostate cancer. We discuss the pathology of prostate inflammation, and consider approaches for assessing the tumor immune microenvironment in epidemiological studies. We review emerging clinical therapies targeting immune biology within the context of prostate cancer. Finally, we consider potentially modifiable risk factors and corresponding lifestyle interventions that may affect prostate inflammation, impacting outcomes. These emerging insights will provide some hints for the development of treatment and prevention strategies for advanced and lethal prostate cancer.

Personalized 5-Year Prostate Cancer Risk Prediction Model in Korea Based on Nationwide Representative Data

Prostate cancer is the fourth most common cause of cancer in men in Korea, and there has been a rapid increase in cases. In the present study, we constructed a risk prediction model for prostate cancer using representative data from Korea. Participants who completed health examinations in 2009, based on the Korean National Health Insurance database, were eligible for the present study. The crude and adjusted risks were explored with backward selection using the Cox proportional hazards model to identify possible risk variables. Risk scores were assigned based on the adjusted hazard ratios, and the standardized points for each risk factor were proportional to the β-coefficient. Model discrimination was assessed using the concordance statistic (c-statistic), and calibration ability was assessed by plotting the mean predicted probability against the mean observed probability of prostate cancer. Among the candidate predictors, age, smoking intensity, body mass index, regular exercise, presence of type 2 diabetes mellitus, and hypertension were included. Our risk prediction model showed good discrimination (c-statistic: 0.826, 95% confidence interval: 0.821-0.832). The relationship between model predictions and actual prostate cancer development showed good correlation in the calibration plot. Our prediction model for individualized prostate cancer risk in Korean men showed good performance. Using easily accessible and modifiable risk factors, this model can help individuals make decisions regarding prostate cancer screening.

Cancer incidence and cancer death in relation to tobacco smoking in a population-based Australian cohort study

Tobacco smoke is a known carcinogen, but the magnitude of smoking-related cancer risk depends on country-specific, generational smoking patterns. We quantified cancer risk in relation to smoking in a population-based cohort, the 45 and Up Study (2006-2009) in New South Wales, Australia. Cox proportional hazards regressions estimated adjusted hazard ratios (HR) by self-reported smoking history at baseline (2006-2009) for incident, primary cancers via linkage to cancer registry data to 2013 and cancer death data to 2015. Among 229 028 participants aged ≥45 years, 18 475 cancers and 5382 cancer deaths occurred. Current-smokers had increased risks of all cancers combined (HR = 1.42, 95% confidence interval [CI], 1.34-1.51), cancers of the lung (HR = 17.66, 95%CI, 14.65-21.29), larynx (HR = 11.29, 95%CI, 5.49-23.20), head-and-neck (HR = 2.53, 95%CI, 1.87-3.41), oesophagus (HR = 3.84, 95%CI, 2.33-6.35), liver (HR = 4.07, 95%CI, 2.55-6.51), bladder (HR = 3.08, 95%CI, 2.00-4.73), pancreas (HR = 2.68, 95%CI, 1.93-3.71), colorectum (HR = 1.31, 95%CI, 1.09-1.57) and unknown primary site (HR = 3.26, 95%CI, 2.19-4.84) versus never-smokers. Hazards increased with increasing smoking intensity; compared to never-smokers, lung cancer HR = 9.22 (95%CI, 5.14-16.55) for 1-5 cigarettes/day and 38.61 (95%CI, 25.65-58.13) for >35 cigarettes/day. Lung cancer risk was lower with quitting at any age but remained higher than never-smokers for quitters aged >25y. By age 80y, an estimated 48.3% of current-smokers (41.1% never-smokers) will develop cancer, and 14% will develop lung cancer, including 7.7% currently smoking 1-5 cigarettes/day and 26.4% for >35 cigarettes/day (1.0% never-smokers). Cancer risk for Australian smokers is significant, even for 'light' smokers. These contemporary estimates underpin the need for continued investment in strategies to prevent smoking uptake and facilitate cessation, which remain key to reducing cancer morbidity and mortality worldwide.

Smoking, alcohol consumption, and cancer: A mendelian randomisation study in UK Biobank and international genetic consortia participants

BACKGROUND

Smoking is a well-established cause of lung cancer and there is strong evidence that smoking also increases the risk of several other cancers. Alcohol consumption has been inconsistently associated with cancer risk in observational studies. This mendelian randomisation (MR) study sought to investigate associations in support of a causal relationship between smoking and alcohol consumption and 19 site-specific cancers.

METHODS AND FINDINGS

We used summary-level data for genetic variants associated with smoking initiation (ever smoked regularly) and alcohol consumption, and the corresponding associations with lung, breast, ovarian, and prostate cancer from genome-wide association studies consortia, including participants of European ancestry. We additionally estimated genetic associations with 19 site-specific cancers among 367,643 individuals of European descent in UK Biobank who were 37 to 73 years of age when recruited from 2006 to 2010. Associations were considered statistically significant at a Bonferroni corrected p-value below 0.0013. Genetic predisposition to smoking initiation was associated with statistically significant higher odds of lung cancer in the International Lung Cancer Consortium (odds ratio [OR] 1.80; 95% confidence interval [CI] 1.59-2.03; p = 2.26 × 10-21) and UK Biobank (OR 2.26; 95% CI 1.92-2.65; p = 1.17 × 10-22). Additionally, genetic predisposition to smoking was associated with statistically significant higher odds of cancer of the oesophagus (OR 1.83; 95% CI 1.34-2.49; p = 1.31 × 10-4), cervix (OR 1.55; 95% CI 1.27-1.88; p = 1.24 × 10-5), and bladder (OR 1.40; 95% CI 1.92-2.65; p = 9.40 × 10-5) and with statistically nonsignificant higher odds of head and neck (OR 1.40; 95% CI 1.13-1.74; p = 0.002) and stomach cancer (OR 1.46; 95% CI 1.05-2.03; p = 0.024). In contrast, there was an inverse association between genetic predisposition to smoking and prostate cancer in the Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome consortium (OR 0.90; 95% CI 0.83-0.98; p = 0.011) and in UK Biobank (OR 0.90; 95% CI 0.80-1.02; p = 0.104), but the associations did not reach statistical significance. We found no statistically significant association between genetically predicted alcohol consumption and overall cancer (n = 75,037 cases; OR 0.95; 95% CI 0.84-1.07; p = 0.376). Genetically predicted alcohol consumption was statistically significantly associated with lung cancer in the International Lung Cancer Consortium (OR 1.94; 95% CI 1.41-2.68; p = 4.68 × 10-5) but not in UK Biobank (OR 1.12; 95% CI 0.65-1.93; p = 0.686). There was no statistically significant association between alcohol consumption and any other site-specific cancer. The main limitation of this study is that precision was low in some analyses, particularly for analyses of alcohol consumption and site-specific cancers.

CONCLUSIONS

Our findings support the well-established relationship between smoking and lung cancer and suggest that smoking may also be a risk factor for cancer of the head and neck, oesophagus, stomach, cervix, and bladder. We found no evidence supporting a relationship between alcohol consumption and overall or site-specific cancer risk.

Prostate Cancer and Asbestos: A Systematic Review and Meta-Analysis

INTRODUCTION

Asbestos-related diseases and cancers represent a major public health concern.

OBJECTIVE

To conduct a systematic review and meta-analysis to demonstrate that asbestos exposure increases the risk of prostate cancer.

METHODS

The PubMed, Cochrane Library, Embase, and ScienceDirect databases were searched using the keywords (prostate cancer OR prostatic neoplasm) AND (asbestos* OR crocidolite* OR chrysotile* OR amphibole* OR amosite*). To be included, articles needed to describe our primary outcome: Risk of prostate cancer after any asbestos exposure.

RESULTS

We included 33 studies with 15,687 cases of prostate cancer among 723,566 individuals. Asbestos exposure increased the risk of prostate cancer (effect size = 1.10, 95% confidence interval [CI] = 1.05-1.15). When we considered mode of absorption, respiratory inhalation increased the risk of prostate cancer (1.10, 95% CI = 1.05-1.14). Both environmental and occupational exposure increased the risk of prostate cancer (1.25, 95% CI = 1.01-1.48; and 1.07, 1.04-1.10, respectively). For type of fibers, the amosite group had an increased risk of prostate cancer (1.12, 95% CI = 1.05-1.19), and there were no significant results for the chrysotile/crocidolite group. The risk was higher in Europe (1.12, 95% CI = 1.05-1.19), without significant results in other continents.

DISCUSSION

Asbestos exposure seems to increase prostate cancer risk. The main mechanism of absorption was respiratory. Both environmental and occupational asbestos exposure were linked to increased risk of prostate cancer.

CONCLUSION

Patients who were exposed to asbestos should possibly be encouraged to complete more frequent prostate cancer screening.

Influence of Diet and Nutrition on Prostate Cancer

The incidence of prostate cancer (PCa) displays widespread regional differences, probably owing to differences in dietary habits. Nutrients, including fat, protein, carbohydrates, vitamins (vitamin A, D, and E), and polyphenols, potentially affect PCa pathogenesis and progression, as previously reported using animal models; however, clinical studies have reported controversial results for almost all nutrients. The effects of these nutrients may be manifested through various mechanisms including inflammation, antioxidant effects, and the action of sex hormones. Dietary patterns including the Western and Prudent patterns also influence the risk of PCa. Recent studies reported that the gut microbiota contribute to tumorigenesis in some organs. Diet composition and lifestyle have a direct and profound effect on the gut bacteria. Human studies reported an increase in the abundance of specific gut bacteria in PCa patients. Although there are few studies concerning their relationship, diet and nutrition could influence PCa, and this could be mediated by gut microbiota. An intervention of dietary patterns could contribute to the prevention of PCa. An intervention targeting dietary patterns may thus help prevent PCa.

GWAS of smoking behaviour in 165,436 Japanese people reveals seven new loci and shared genetic architecture

Cigarette smoking is a risk factor for a wide range of human diseases¹. To investigate the genetic components associated with smoking behaviours in the Japanese population, we conducted a genome-wide association study of four smoking-related traits using up to 165,436 individuals. In total, we identified seven new loci, including three loci associated with the number of cigarettes per day (EPHX2-CLU, RET and CUX2-ALDH2), three loci associated with smoking initiation (DLC1, CXCL12-TMEM72-AS1 and GALR1-SALL3) and LINC01793-MIR4432HG, associated with the age of smoking initiation. Of these, three loci (LINC01793-MIR4432HG, CXCL12-TMEM72-AS1 and GALR1-SALL3) were found by conducting an additional sex-stratified genome-wide association study. This additional analysis showed heterogeneity of effects between sexes. The cross-sex linkage disequilibrium score regression^2,3 analysis also indicated that the genetic component of smoking initiation was significantly different between the sexes. Cross-trait linkage disequilibrium score regression analysis and trait-relevant tissue analysis showed that the number of cigarettes per day has a specific genetic background distinct from those of the other three smoking behaviours. We also report 11 diseases that share genetic basis with smoking behaviours. Although the current study should be carefully considered owing to the lack of replication samples, our findings characterized the genetic architecture of smoking behaviours. Further studies in East Asian populations are warranted to confirm our findings.

Clinically occult prostate cancer cases may distort the effect of testosterone replacement therapy on risk of PCa

BACKGROUND

Although prostate cancer (PCa) screening is conducted before testosterone replacement therapy (TRT), clinically occult PCa cases may exist.

METHODS

To evaluate whether the possible inclusion of occult PCa cases distorts the effect of TRT on risk of PCa, we followed 776 hypogonadal males (TRT = 400, non-TRT = 376) from a urology center in Germany from 2004 to 2016, with a mean follow-up period of 7 years. We assumed occult cases might take 1-2 years (latency period) to become clinically detectable after receiving TRT. We selected several latency periods (12/18/24 months) and compared the risk of PCa in the TRT and non-TRT group over the latency period, from the end of latency period till the end of follow-up, and over the whole follow-up time.

RESULTS

Overall, 26 PCa cases occurred in the non-TRT group vs 9 cases in the TRT group. Within 18 months of follow-up, 9 cases occurred in the TRT group vs 0 cases in the non-TRT group; from the end of 18 months till the end of follow-up, 26 cases occurred in the non-TRT group vs 0 cases in the TRT group. The adjusted table showed seemingly adverse effects of TRT on PCa development within 18 months (p = 0.0301) and beneficial effects from the end of 18 months till the end of follow-up (p = 0.0069). Similar patterns were observed for 12 or 24 months as the latency period.

CONCLUSIONS

TRT may make occult PCa cases detectable within early phase of treatment and present a beneficial effect in the long run. Future longitudinal studies are needed to confirm findings from our exploratory analyses.

Impact of tobacco smoking on the risk of developing 25 different cancers in the UK: a retrospective study of 422,010 patients followed for up to 30 years

BACKGROUND

The aim of this study was to analyze the impact of tobacco smoking on the risk of developing 25 different cancers in patients followed for up to 30 years in general practices in the UK.

METHODS

This study included all individuals with at least one visit to one of 196 general practitioners' offices in the UK between January 1988 and December 2008 (index date). Only individuals with documented smoking status were included. Smokers and non-smokers were matched (1:1) by age, gender, index year, body mass index, and physician. The main outcome of the study was the risk of cancer as a function of smoking status. Data regarding a total of 25 cancers were available for the present analysis. The risk of cancer was analyzed using Cox's regression model.

RESULTS

The present retrospective study included 211,005 smokers and 211,005 non-smokers. The mean age was 36.5 years (SD = 12.5 years) in men and 34.3 years (SD = 13.1 years) in women. There was a slightly positive association between smoking and any cancer in both men (HR = 1.07) and women (HR = 1.03). Smoking was further found to be positively associated with several cancers, such as liver cancer, bladder and kidney cancers, pancreas cancer, and lymphoma. By contrast, the use of tobacco was negatively associated with the risk of developing skin cancer, prostate cancer, multiple myeloma, endometrial carcinoma, or breast cancer.

CONCLUSIONS

Smoking increased the overall risk of cancer in primary care practices in the UK. In addition, smoking was predominantly positively and less frequently negatively associated with numerous specific cancers.

Latest Evidence on the Impact of Smoking, Sports, and Sexual Activity as Modifiable Lifestyle Risk Factors for Prostate Cancer Incidence, Recurrence, and Progression: A Systematic Review of the Literature by the European Association of Urology Section of Oncological Urology (ESOU)

CONTEXT

Smoking, sexual activity, and physical activity (PA) are discussed as modifiable lifestyle factors associated with prostate cancer (PCa) development and progression.

OBJECTIVE

To evaluate the available evidence concerning the association of smoking, sexual activity, and sports and exercise on PCa risk, treatment outcome, progression, and cancer-specific mortality.

EVIDENCE ACQUISITION

A systematic review of studies published between 2007 and 2017 using MEDLINE (via PubMed), Cochrane Central Register of Controlled Trials, and Web of Science databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement criteria was conducted.

EVIDENCE SYNTHESIS

While data concerning the impact of smoking on PCa development remain conflicting, there is robust evidence that smoking is associated with aggressive tumor features and worse cancer-related outcome, which seems to be maintained for 10 yr after smoking cessation. Less convincing and limited evidence exists for the association of sexual activity with PCa risk. The findings related to PA and PCa support the inference that exercise might be a useful factor in the prevention of PCa and tumor progression, while it is not finally proved under which specific conditions PA might be protective against disease development.

CONCLUSIONS

Smoking is associated with aggressive tumor features and worse cancer-related prognosis; as this negative impact seems to be maintained for 10yr after smoking cessation, urologists should advise men to quit smoking latest at PCa diagnosis to improve their prognosis. As several studies indicate a positive impact of exercise on tumor development, progression, and treatment outcome, it is certainly reasonable to advocate an active lifestyle. Least convincing evidence is available for the interaction of sexual activity and PCa, and well-conducted and longitudinal studies are clearly necessary to evaluate whether the suggested associations between PCa risk and sexual behavior are real or spurious.

PATIENT SUMMARY

In this systematic review, we looked at the impact of smoking, sexual activity, and sports and exercise on prostate cancer risk and outcome after treatment. While the evidence for sexual activity is not overall clear, we found that smoking might lead to more aggressive cancers and result in worse treatment outcome. Physical activity might prevent prostate cancer and improve cancer-related outcomes as well. Hence, it is certainly reasonable to advocate an active lifestyle and advise men to quit smoking.

Functional role and tobacco smoking effects on methylation of CYP1A1 gene in prostate cancer

Cytochrome P450 (CYP) 1A1 is a phase I enzyme that can activate various compounds into reactive forms and thus, may contribute to carcinogenesis. In this study, we investigated the expression, methylation status, and functional role of CYP1A1 on prostate cancer cells. Increased expression of CYP1A1 was observed in all cancer lines (PC-3, LNCaP, and DU145) compared to BPH-1 (P < 0.05); and was enhanced further by 5-aza-2′-deoxycytidine treatment (P < 0.01). Methylation-specific PCR (MSP) and sequencing of bisulfite-modified DNA of the xenobiotic response element (XRE) enhancer site XRE-1383 indicated promoter methylation as a regulator of CYP1A1 expression. In tissue, microarrays showed higher immunostaining of CYP1A1 in prostate cancer than normal and benign prostatic hyperplasia (BPH; P < 0.001), and methylation analyses in clinical specimens revealed significantly lower methylation levels in cancer compared to BPH at all enhancer sites analyzed (XRE-1383, XRE-983, XRE-895; P < 0.01). Interestingly, smoking affected the XRE-1383 site where the methylation level was much lower in cancer tissues from smokers than non-smokers (P < 0.05). CYP1A1 levels are thus increased in prostate cancer and to determine the functional effect of CYP1A1 on cells, we depleted the gene in LNCaP and DU145 by siRNA. We observe that CYP1A1 knockdown decreased cell proliferation (P < 0.05) and increased apoptosis (P < 0.01) in both cell lines. We analyzed genes affected by CYP1A1 silencing and found that apoptosis-related BCL2 was significantly down-regulated. This study supports an oncogenic role for CYP1A1 in prostate cancer via promoter hypomethylation that is influenced by tobacco smoking, indicating CYP1A1 to be a promising target for prostate cancer treatment.

Smoking and prostate cancer: a life course analysis

Background

Inconsistent associations between smoking status and prostate cancer (PC) could be due to exposure assessment error. Reconstructing smoking behaviors over the life course could reduce exposure assessment error.

Methods

As part of a case-control study, we identified 402 incident and histologically confirmed PC cases that were matched by age (±5 years) to 805 population controls. Through direct interview, we obtained information about: age at smoking onset, intensity and frequency of cigarette smoking at different life stages, and smoking cessation age. Smoking status at interview and average smoking index over the lifetime (packs/year) were estimated. Life course smoking patterns were obtained applying the k-means+ method for longitudinal data to the smoking index (pack/year) for each life stage.

Results

Two life-course smoking patterns were identified among ever smokers: “pattern A” characterized by males who reported low and constant smoking intensity (87.8%), and “pattern B” (12.2%) males with an initial period of low intensity, followed by an increase during the second period. Compared to never smokers, pattern B was associated with higher poorly differentiated PC, (OR 2.30; 95% CI 1.21–4.38). No association was observed with average smoking index.

Conclusion

Life course smoking patterns seem to capture the smoking variability during life course and reduce the likelihood of reverse causation. Using this assessment strategy our findings support the potential role of tobacco smoking in PC, particularly poorly differentiated PC. Prospective studies with comprehensive smoking history during the lifetime are needed to confirm these findings.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4065-7) contains supplementary material, which is available to authorized users.

Lifestyle Risk Prediction Model for Prostate Cancer in a Korean Population

PURPOSE

The use of prostate-specific antigen as a biomarker for prostate cancer (PC) has been controversial and is, therefore, not used by many countries in their national health screening programs. The biological characteristics of PC in East Asians including Koreans and Japanese are different from those in the Western populations. Potential lifestyle risk factors for PC were evaluated with the aim of developing a risk prediction model.

Materials and Methods

A total of 1,179,172 Korean men who were cancer free from 1996 to 1997, had taken a physical examination, and completed a lifestyle questionnaire, were enrolled in our study to predict their risk for PC for the next eight years, using the Cox proportional hazards model. The model's performance was evaluated using the C-statistic and Hosmer‒Lemeshow type chi-square statistics.

RESULTS

The risk prediction model studied age, height, body mass index, glucose levels, family history of cancer, the frequency of meat consumption, alcohol consumption, smoking status, and physical activity, which were all significant risk factors in a univariate analysis. The model performed very well (C statistic, 0.887; 95% confidence interval, 0.879 to 0.895) and estimated an elevated PC risk in patients who did not consume alcohol or smoke, compared to heavy alcohol consumers (hazard ratio [HR], 0.78) and current smokers (HR, 0.73) (p < 0.001).

CONCLUSION

This model can be used for identifying Korean and other East Asian men who are at a high risk for developing PC, as well as for cancer screening and developing preventive health strategies.

Oncologic Effect of Cumulative Smoking Exposure in Patients Treated With Salvage Radical Prostatectomy for Radiation-recurrent Prostate Cancer

INTRODUCTION

The purpose of the present study was to investigate the association of smoking with biochemical recurrence (BCR) and metastasis in radiation-recurrent prostate cancer (PCa) patients undergoing salvage radical prostatectomy (SRP).

PATIENTS AND METHODS

A total of 214 patients treated with SRP for radiation-recurrent PCa in 5 tertiary referral centers were included from January 2007 to December 2015. Kaplan-Meier analyses were used to assess the time to BCR and metastasis. Pre- and postoperative multivariable Cox proportional hazard regression models were fitted.

RESULTS

Overall, 120 (56.1%), 49 (22.9%), and 45 (21%) patients were never, former, and current smokers, respectively. Low-, medium-, and high-cumulative smoking exposure was registered in 59.8%, 16.4%, and 23.8% of cases, respectively. Patients with high cumulative smoking exposure had a significantly greater rate of a pathologic Gleason score of ≥ 8 (P = .01) and extracapsular extension (P = .004). Smoking status, cumulative smoking exposure, intensity, and duration were significantly associated with BCR-free survival (P < .001 for all). Smoking status, cumulative smoking exposure, and smoking intensity were significantly associated with metastasis-free survival (P = .03 for all). High cumulative smoking exposure was independently associated with BCR in both pre- (hazard ratio, 2.23; P = .001) and postoperative (hazard ratio, 1.64; P = .04) multivariable models adjusted for the effects of established clinicopathologic features. Smoking cessation did not affect either BCR- or metastasis-free survival (P = .56 and P = .40, respectively).

CONCLUSION

High cumulative smoking exposure was associated with the biologic and clinical aggressiveness of PCa in patients treated with SRP for radiation-recurrent disease. Smoking is a modifiable risk factor that detrimentally affected the outcomes, even in patients with advanced PCa.

Smoking increased the risk of prostate cancer with grade group ≥ 4 and intraductal carcinoma in a prospective biopsy cohort

OBJECTIVE

To investigate the association between smoking and different prostate cancer (PCa) pathological subtypes incidence in Chinese men.

PATIENTS AND METHODS

We prospectively included 1795 patients who underwent prostate biopsies in one tertiary center between March 2013 and April 2016. Clinical data and biopsy outcomes were collected. Logistic regression was used to evaluate the association between cigarette smoking and PCa incidence.

RESULTS

A total of 737 men, 480 men and 58 men were diagnosed with PCa, high-grade PCa (HGPCa, grade group ≥ 4 as accepted by the 2014 ISUP) and intraductal carcinoma of the prostate (IDC-P), respectively. Current smokers had a significantly higher risk of HGPCa than never smokers (OR = 1.89, 95%CI: 1.44-2.48). No such association was observed for low-grade disease and cigarette smoking (OR = 0.84, 95%CI: 0.61-1.16). In a sub-analysis, men who had smoked longer than 30 years had a higher risk of HGPCa, compared with men who had smoked fewer than 30 years (OR = 1.50, 95%CI: 1.09-2.06). Current smokers were more likely to develop IDC-P than never smokers (OR = 2.29, 95%CI: 1.14-4.59).

CONCLUSION

Among men in this Chinese biopsy cohort, current smoking was associated with highly malignant PCa incidence, such as HGPCa and IDC-P. The duration of smoking may be associated with HGPCa.

[What do prostate cancer patients know about smoking? : Results of a bicentric questionnaire study (KRAUT study)]

BACKGROUND

According to the results of a recent meta-analysis, cancer-specific mortality of prostate cancer (PCA) patients is enhanced by 24 % in case of a positive smoking history with a dose-dependent impact of smoking. Until now it is unknown whether this information actually reaches the patients and how extensively an informational discussion about this topic is pursued by physicians.

OBJECTIVE

Three study hypotheses were defined: (1) the knowledge of PCA patients about the potential relationship between tumor progression and cigarette consumption is low, (2) only in rare cases has a clear statement been provided by treating physicians including the explicit advice to stop smoking, and (3) there was a direct association between tumor stage and the extent of cigarette consumption.

MATERIALS AND METHODS

A questionnaire comprising 23 items was developed and validated with 25 uro-oncological patients prior to study start. Between September 2013 and December 2014 a total of 124 PCA patients (median age 65 years) from two urology departments were included in this questionnaire-based survey.

RESULTS

The study population comprised 43 % (n = 54), 39 % (n = 48), and 18 % (n = 22) nonsmokers, former smokers and active smokers, respectively. Active and former smokers differed insignificantly in the number of pack-years only (24.8 vs. 23.7 years, p = 0.995). Of the patients, 56 % regarded an influence of cigarette consumption on the PCA-specific prognosis as possible. However, because a significant (p < 0.001) number of patients wrongly suspected smoking to be causative for PCA development, their knowledge about PCA prognosis is supposedly not based on adequate knowledge. Two of 22 active smokers (9.1 %), 5 of 48 former smokers (10.4 %), and 2 of 54 nonsmokers (3.7 %) had an informational discussion with their urologist about the association of cigarette consumption and PCA-related prognosis (a further 9.1, 4.2 and 3.7 %, respectively, received this information solely from other medical specialties). Only 1 of 22 active smokers (4.5 %) was offered medical aids for smoking cessation by the general practitioner; none of the patients received such support by an urologist. There was no association between a positive smoking history or number of pack-years and PCA tumor stage.

CONCLUSIONS

Education of PCA patients about the relationship between cigarette consumption and cancer-related prognosis is currently inadequate. Following the latest findings on this topic, urologists should pursue informational discussions with their patients, thereby strengthening their position as the primary contact person for decision making in PCA management.

Quantification of the smoking-associated cancer risk with rate advancement periods: meta-analysis of individual participant data from cohorts of the CHANCES consortium

BACKGROUND

Smoking is the most important individual risk factor for many cancer sites but its association with breast and prostate cancer is not entirely clear. Rate advancement periods (RAPs) may enhance communication of smoking related risk to the general population. Thus, we estimated RAPs for the association of smoking exposure (smoking status, time since smoking cessation, smoking intensity, and duration) with total and site-specific (lung, breast, colorectal, prostate, gastric, head and neck, and pancreatic) cancer incidence and mortality.

METHODS

This is a meta-analysis of 19 population-based prospective cohort studies with individual participant data for 897,021 European and American adults. For each cohort we calculated hazard ratios (HRs) for the association of smoking exposure with cancer outcomes using Cox regression adjusted for a common set of the most important potential confounding variables. RAPs (in years) were calculated as the ratio of the logarithms of the HRs for a given smoking exposure variable and age. Meta-analyses were employed to summarize cohort-specific HRs and RAPs.

RESULTS

Overall, 140,205 subjects had a first incident cancer, and 53,164 died from cancer, during an average follow-up of 12 years. Current smoking advanced the overall risk of developing and dying from cancer by eight and ten years, respectively, compared with never smokers. The greatest advancements in cancer risk and mortality were seen for lung cancer and the least for breast cancer. Smoking cessation was statistically significantly associated with delays in the risk of cancer development and mortality compared with continued smoking.

CONCLUSIONS

This investigation shows that smoking, even among older adults, considerably advances, and cessation delays, the risk of developing and dying from cancer. These findings may be helpful in more effectively communicating the harmful effects of smoking and the beneficial effect of smoking cessation.

Development and Application of a Lifestyle Score for Prevention of Lethal Prostate Cancer

BACKGROUND

Several lifestyle factors have been associated with risk of lethal prostate cancer, but little is known about their combined effect. Our objective was to develop and apply a lifestyle score for prevention of lethal prostate cancer.

METHODS

We developed a lifestyle score among 42 701 men in the Health Professionals Follow-up Study (HPFS) followed from 1986 to 2010 and applied it among 20 324 men in the Physicians' Health Study (PHS) followed from 1982 to 2010. One point was given for each of: not currently smoking or quit 10 or more years ago, body mass index under 30 kg/m(2), high vigorous physical activity, high intake of tomatoes and fatty fish, and low intake of processed meat. Diet-only scores (range = 0-3) and total scores (range = 0-6) were calculated. We used multivariable Cox proportional hazards regression to estimate the risk of lethal prostate cancer, adjusting for potential risk factors of lethal prostate cancer. All statistical tests were two-sided.

RESULTS

We observed 576 lethal prostate cancer events in HPFS and 337 in PHS. Men with 5-6 vs 0-1 points had a 68% decreased risk of lethal prostate cancer (hazard ratio [HR] = 0.32, 95% confidence interval [CI] = 0.19 to 0.52) in HPFS and a non-statistically significant 38% decreased risk (HR = 0.62, 95% CI = 0.30 to 1.26) in PHS. For dietary factors only, men with 3 vs 0 points had a 46% decreased risk (HR = 0.54, 95% CI = 0.30 to 0.96) in the HPFS and a non-statistically significant 30% decreased risk (HR = 0.70, 95% CI = 0.40 to 1.23) in PHS.

CONCLUSIONS

Adhering to a healthy lifestyle, defined by not smoking, normal body weight, high physical activity, and a healthy diet, may lower risk of lethal prostate cancer.

Carotenoids, retinol, tocopherols, and prostate cancer risk: pooled analysis of 15 studies

BACKGROUND

Individual studies have suggested that circulating carotenoids, retinol, or tocopherols may be associated with prostate cancer risk, but the studies have not been large enough to provide precise estimates of associations, particularly by stage and grade of disease.

OBJECTIVE

The objective of this study was to conduct a pooled analysis of the associations of the concentrations of 7 carotenoids, retinol, α-tocopherol, and γ-tocopherol with risk of prostate cancer and to describe whether any associations differ by stage or grade of the disease or other factors.

DESIGN

Principal investigators of prospective studies provided individual participant data for prostate cancer cases and controls. Risk by study-specific fifths of each biomarker was estimated by using multivariable-adjusted conditional logistic regression in matched case-control sets.

RESULTS

Data were available for up to 11,239 cases (including 1654 advanced stage and 1741 aggressive) and 18,541 controls from 15 studies. Lycopene was not associated with overall risk of prostate cancer, but there was statistically significant heterogeneity by stage of disease, and the OR for aggressive disease for the highest compared with the lowest fifth of lycopene was 0.65 (95% CI: 0.46, 0.91; P-trend = 0.032). No other carotenoid was significantly associated with overall risk of prostate cancer or with risk of advanced-stage or aggressive disease. For retinol, the OR for the highest compared with the lowest fifth was 1.13 (95% CI: 1.04, 1.22; P-trend = 0.015). For α-tocopherol, the OR for the highest compared with the lowest fifth was 0.86 (95% CI: 0.78, 0.94; P-trend < 0.001), with significant heterogeneity by stage of disease; the OR for aggressive prostate cancer was 0.74 (95% CI: 0.59, 0.92; P-trend = 0.001). γ-Tocopherol was not associated with risk.

CONCLUSIONS

Overall prostate cancer risk was positively associated with retinol and inversely associated with α-tocopherol, and risk of aggressive prostate cancer was inversely associated with lycopene and α-tocopherol. Whether these associations reflect causal relations is unclear.

Cigarette smoke modulates PC3 prostate cancer cell migration by altering adhesion molecules and the extracellular matrix

Prostate cancer (PCa) is the second leading cause of cancer-related mortality among American males. Studies suggest that cigarette smoking is associated with the progression of PCa; however, the molecular mechanisms underlying this process have not been extensively investigated. PCa progression is characterized by increased cell migration and alterations in extracellular matrix (ECM)- and cell adhesion molecule (CAM)-related gene expression. In the present study, the influence of cigarette smoke medium (SM) on cell migration and on the expression of ECM- and CAM-related genes in PC3 prostate adenocarcinoma cells was investigated. According to a wound-healing assay, SM treatment promoted PC3 cell migration. RNA expression levels from SM-treated and control cells were analyzed using a polymerase chain reaction (PCR) array. Of 84 genes analyzed, 27.38% (23/84) exhibited a ≥2-fold change in threshold cycle in PC3 cells following 0.5% SM treatment. Functional gene grouping analysis demonstrated that SM treatment modulated the RNA transcription of approximately 18.4% of CAMs and 33.93% of ECM-related genes. Quantitative PCR analysis showed that SM treatment led to a significant decrease in transcription levels of the following genes: Collagen 5 α-1(V), connective tissue growth factor, integrin β-2, kallmann syndrome 1, laminin α 3, matrix metallopeptidase 7 (MMP7), MMP13, secreted protein acidic cysteine-rich, thrombospondin-2 and versican; and that SM significantly increased the transcription levels of MMP2 and MMP12. Furthermore, MMP2 knockdown significantly reduced the migration of SM-treated PC3 cells. The present study provides novel insights into the association of cigarette smoking with PCa progression, via the alteration of ECM/CAM interactions.

Racial/ethnic differences in lifestyle-related factors and prostate cancer risk: the Multiethnic Cohort Study

PURPOSE

Older age, African ancestry, and family history of prostate cancer are well-established risk factors for prostate cancer, and all are non-modifiable. Various lifestyle factors have been examined in relation to prostate cancer risk, including diet, obesity, and physical activity; however, none of them has been consistently related to risk. In the Multiethnic Cohort Study, we investigated whether lifestyle-related factors are associated with prostate cancer risk and whether such factors explain the racial/ethnic differences in risk.

METHODS

During a mean follow-up of 13.9 years, 7,115 incident cases were identified among 75,216 white, African-American, Native Hawaiian, Japanese American, and Latino men. Cox proportional hazards models were used to calculate relative risks (RRs) and 95 % confidence intervals (95 % CIs) for prostate cancer.

RESULTS

Among selected lifestyle-related factors including body mass index, height, education, physical activity, and intakes of alcohol, calcium, legumes, lycopene, and selenium, only smoking (RR for current (≥20 cigarettes/day) vs. never smoking = 0.72; 95 % CI 0.63-0.83) and history of diabetes (RR for yes vs. no = 0.78; 95 % CI 0.72-0.85) were significantly associated with prostate cancer risk. Compared to whites, the risk of incident prostate cancer was twofold higher in African-Americans and 16 % higher in Latinos. Additional adjustment for a history of PSA testing did not change the results.

CONCLUSIONS

The findings suggest that racial/ethnic differences in prostate cancer risk are not explained by the lifestyle factors examined and that underlying genetic factors may be involved.

Dietary cadmium intake and risk of prostate cancer: a Danish prospective cohort study

BACKGROUND

Cadmium is classified as a human lung carcinogen based on evidence from high-exposure occupational settings. Though cadmium has no physiological role, increasing evidence suggests cadmium may mimic steroid hormones. This dual ability of being carcinogenic and hormone-like makes cadmium a concern for hormone-related cancers. Causes of prostate cancer are not clear, but steroid hormones, particularly androgens and probably estrogens, may be involved. Cadmium has been positively associated with prostate cancer in occupationally exposed men. In non-occupationally exposed populations, diet and smoking are the main sources of cadmium exposure. The aim of this study was to investigate the association between dietary cadmium intake and prostate cancer risk in Danish men.

METHODS

Dietary cadmium intake was estimated in the Danish Diet, Cancer and Health cohort at baseline 1993-97. The estimates were based on a 192 item semi-quantitative food frequency questionnaire and cadmium contents in all food items. Among 26,778 men we identified 1,567 prostate cancer cases from baseline through December 31, 2010 using the Danish Cancer Registry. The association between dietary cadmium intake and prostate cancer risk was analysed using Cox regression models.

RESULTS

We did not find an association between dietary cadmium intake and prostate cancer risk (adjusted incidence rate ratio per 10 μg day(-1) = 0.98 (95% CI = 0.88-1.10)). The association did not differ according to aggressiveness of prostate cancer. Educational level, smoking status, BMI, zinc or iron intake did not modify the association.

CONCLUSIONS

In our study, we did not find an association between dietary cadmium intake and prostate cancer risk in a cohort of Danish men.

Dietary cadmium intake and risk of prostate cancer: a Danish prospective cohort study

BACKGROUND

Cadmium is classified as a human lung carcinogen based on evidence from high-exposure occupational settings. Though cadmium has no physiological role, increasing evidence suggests cadmium may mimic steroid hormones. This dual ability of being carcinogenic and hormone-like makes cadmium a concern for hormone-related cancers. Causes of prostate cancer are not clear, but steroid hormones, particularly androgens and probably estrogens, may be involved. Cadmium has been positively associated with prostate cancer in occupationally exposed men. In non-occupationally exposed populations, diet and smoking are the main sources of cadmium exposure. The aim of this study was to investigate the association between dietary cadmium intake and prostate cancer risk in Danish men.

METHODS

Dietary cadmium intake was estimated in the Danish Diet, Cancer and Health cohort at baseline 1993-97. The estimates were based on a 192 item semi-quantitative food frequency questionnaire and cadmium contents in all food items. Among 26,778 men we identified 1,567 prostate cancer cases from baseline through December 31, 2010 using the Danish Cancer Registry. The association between dietary cadmium intake and prostate cancer risk was analysed using Cox regression models.

RESULTS

We did not find an association between dietary cadmium intake and prostate cancer risk (adjusted incidence rate ratio per 10 μg day(-1) = 0.98 (95% CI = 0.88-1.10)). The association did not differ according to aggressiveness of prostate cancer. Educational level, smoking status, BMI, zinc or iron intake did not modify the association.

CONCLUSIONS

In our study, we did not find an association between dietary cadmium intake and prostate cancer risk in a cohort of Danish men.

Tobacco smoking, polymorphisms in carcinogen metabolism enzyme genes, and risk of localized and advanced prostate cancer: results from the California Collaborative Prostate Cancer Study

The relationship between tobacco smoking and prostate cancer (PCa) remains inconclusive. This study examined the association between tobacco smoking and PCa risk taking into account polymorphisms in carcinogen metabolism enzyme genes as possible effect modifiers (9 polymorphisms and 1 predicted phenotype from metabolism enzyme genes). The study included cases (n = 761 localized; n = 1199 advanced) and controls (n = 1139) from the multiethnic California Collaborative Case-Control Study of Prostate Cancer. Multivariable conditional logistic regression was performed to evaluate the association between tobacco smoking variables and risk of localized and advanced PCa risk. Being a former smoker, regardless of time of quit smoking, was associated with an increased risk of localized PCa (odds ratio [OR] = 1.3; 95% confidence interval [CI] = 1.0-1.6). Among non-Hispanic Whites, ever smoking was associated with an increased risk of localized PCa (OR = 1.5; 95% CI = 1.1-2.1), whereas current smoking was associated with risk of advanced PCa (OR = 1.4; 95% CI = 1.0-1.9). However, no associations were observed between smoking intensity, duration or pack-year variables, and advanced PCa. No statistically significant trends were seen among Hispanics or African-Americans. The relationship between smoking status and PCa risk was modified by the CYP1A2 rs7662551 polymorphism (P-interaction = 0.008). In conclusion, tobacco smoking was associated with risk of PCa, primarily localized disease among non-Hispanic Whites. This association was modified by a genetic variant in CYP1A2, thus supporting a role for tobacco carcinogens in PCa risk.

A systematic review and meta-analysis of tobacco use and prostate cancer mortality and incidence in prospective cohort studies

CONTEXT

An association between tobacco smoking and prostate cancer (PCa) incidence and mortality was suggested in an earlier meta-analysis of 24 prospective studies in which dose-response associations and risks per unit of tobacco use were not examined.

OBJECTIVE

We investigated the association between several measures of tobacco use and PCa mortality (primary outcome) and incidence (secondary outcome) including dose-response association.

EVIDENCE ACQUISITION

Relevant articles from prospective studies were identified by searching the PubMed and Web of Science databases (through January 21, 2014) and reference lists of relevant articles. Combined relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random effects methods. We also calculated population attributable risk (PAR) for smoking and PCa mortality.

EVIDENCE SYNTHESIS

We included 51 articles in this meta-analysis (11823 PCa deaths, 50349 incident cases, and 4,082,606 cohort participants). Current cigarette smoking was associated with an increased risk of PCa death (RR: 1.24; 95% CI, 1.18-1.31), with little evidence for heterogeneity and publication bias. The number of cigarettes smoked per day had a dose-response association with PCa mortality (p=0.02; RR for 20 cigarettes per day: 1.20). The PAR for cigarette smoking and PCa deaths in the United States and Europe were 6.7% and 9.5%, respectively, corresponding to >10000 deaths/year in these two regions. Current cigarette smoking was inversely associated with incident PCa (RR: 0.90; 95% CI, 0.85-0.96), with high heterogeneity in the results. However, in studies completed in 1995 or earlier (considered as completed before the prostate-specific antigen screening era), ever smoking showed a positive association with incident PCa (RR: 1.06; 95% CI, 1.00-1.12) with little heterogeneity.

CONCLUSIONS

Combined evidence from observational studies shows a modest but statistically significant association between cigarette smoking and fatal PCa. Smoking appears to be a modifiable risk factor for PCa death.

PATIENT SUMMARY

Smoking increases the chance of prostate cancer death. Not smoking prevents this harm and many other tobacco-related diseases.

Smoking and risk of low- and high-grade prostate cancer: results from the REDUCE study

PURPOSE

Although the relationship between smoking and prostate cancer risk is inconsistent, some studies show that smoking is associated with prostate cancer mortality. Whether this reflects delayed diagnosis or direct smoking-related effects is unknown. REDUCE, which followed biopsy-negative men with protocol-dictated prostate-specific antigen (PSA)-independent biopsies at 2 and 4 years, provides an opportunity to evaluate smoking and prostate cancer diagnosis with minimal confounding from screening biases.

EXPERIMENTAL DESIGN

Logistic regression was conducted to test the association between smoking and cancer on the first on-study biopsy (no cancer, low-grade Gleason 4-6, high-grade Gleason 7-10) in REDUCE.

RESULTS

Of 6,240 men with complete data and ≥1 on-study biopsy, 2,937 (45.8%) never smoked, 929 (14.5%) were current smokers, and 2,554 (39.8%) were former smokers. Among men with negative first on-study biopsies, smokers were 36% less likely to receive a second on-study biopsy (P < 0.001). At first on-study biopsy, 941 (14.7%) men had cancer. Both current and former smoking were not significantly associated with either total or low-grade prostate cancer (all P > 0.36). Current (OR = 1.44, P = 0.028) but not former smokers (OR = 1.21, P = 0.12) were at increased risk of high-grade disease. On secondary analysis, there was an interaction between smoking and body mass index (BMI; Pinteraction = 0.017): current smokers with BMI ≤ 25 kg/m(2) had an increased risk of low-grade (OR = 1.54, P = 0.043) and high-grade disease (OR = 2.45, P = 0.002), with null associations for BMI ≥ 25 kg/m(2).

CONCLUSION

Among men with elevated PSA and negative pre-study biopsy in REDUCE, in which biopsies were largely PSA independent, smoking was unrelated to overall prostate cancer diagnosis but was associated with increased risk of high-grade prostate cancer.

Coffee consumption and risk of nonaggressive, aggressive and fatal prostate cancer--a dose-response meta-analysis

BACKGROUND

Existing epidemiological evidence is controversial regarding the possible associations between coffee consumption and risk of prostate cancer (PCa) by aggressiveness of the disease.

MATERIALS AND METHODS

We conducted a random-effects dose-response meta-analysis to assess the relationships between coffee consumption and nonaggressive, aggressive and fatal PCa risk. Studies were identified by a search of Medline and Embase databases to 15 July 2013. We carried out separate analyses by grade (Gleason score: low-grade, high-grade) and stage (TNM staging system: localized, advanced) of the tumors. Nonaggressive tumors were defined as low-grade or localized, while aggressive tumors were defined as high-grade or advanced.

RESULTS

Eight studies (three case-control and five cohort) were included in this meta-analysis. Gleason 7 tumors were classified as high-grade in one study, while in another study, Gleason 7(4 + 3) tumors were classified as high-grade and Gleason 7(3 + 4) as low-grade. In the remaining four studies, Gleason 7 tumors were excluded from the analyses or analyzed separately. The pooled relative risk (RR) for a consumption increment of 3 cups/day was 0.97 [95% confidence interval (CI) 0.92-1.03] for low-grade PCa (n = 6), 0.97 (95% CI 0.94-0.99) for localized PCa (n = 6), 0.89 (95% CI 0.78-1.00) for high-grade PCa (n = 6), 0.95 (95% CI 0.85-1.06) for advanced PCa (n = 6) and 0.89 (95% CI 0.82-0.97) for fatal PCa (n = 4). No evidence of publication bias was observed. Heterogeneity was absent or marginal (I(2) range = 0-26%), with the only exception of the analysis on advanced PCa, where moderate heterogeneity was observed (I(2) = 60%). When restricting the analyses only to those studies that defined high-grade tumors as Gleason 8-10, the inverse association became slightly stronger [RR: 0.84 (95% CI 0.72-0.98); n = 4].

CONCLUSIONS

Results from this dose-response meta-analysis suggest that coffee consumption may be inversely associated with the risk of fatal PCa. No clear evidence of an association with PCa incidence was observed.

Cigarette smoking is associated with an increased risk of biochemical disease recurrence, metastasis, castration-resistant prostate cancer, and mortality after radical prostatectomy: results from the SEARCH database

BACKGROUND

The current study was conducted to analyze the association between cigarette smoking and metastasis (the primary outcome) as well as time to biochemical disease recurrence (BCR), metastasis, castration-resistant prostate cancer (CRPC), and prostate cancer-specific and overall mortality (secondary outcomes) after radical prostatectomy among men from the Shared Equal Access Regional Cancer Hospital cohort.

METHODS

A retrospective analysis was performed of 1450 subjects for whom smoking status was available from preoperative notes. Analysis of baseline characteristics by smoking status was performed using the chi-square and rank sum tests. The association between smoking status and time to the event was analyzed using Kaplan-Meier plots, the log-rank test, and Cox and competing risk models.

RESULTS

A total of 549 men (33%) men were active smokers and 1121 (67%) were nonsmokers at the time of surgery. Current smokers were younger and had a lower body mass index, higher prostate-specific antigen level, and more extracapsular extension and seminal vesicle invasion (all P<.05). A total of 509 patients, 26 patients, 30 patients, 18 patients, and 217 patients, respectively, experienced BCR, metastasis, CRPC, prostate cancer-related death, and any-cause death over a median follow-up of 62 months, 75 months, 61 months, 78 months, and 78 months, respectively. After adjusting for preoperative features, active smoking was found to be associated with an increased risk of BCR (hazards ratio [HR], 1.25; P=.024), metastasis (HR, 2.64; P=.026), CRPC (HR, 2.62; P=.021), and overall mortality (HR, 2.14; P<.001). Similar results were noted after further adjustment for postoperative features, with the exception of BCR (HR, 1.10; P=.335), metastasis (HR, 2.51; P=.044), CRPC (HR, 2.67; P=.015), and death (HR, 2.03; P<.001).

CONCLUSIONS

Among patients undergoing radical prostatectomy, cigarette smoking was associated with an increased risk of metastasis. In addition, smoking was associated with a higher risk of BCR, CRPC, and overall mortality. If confirmed, these data suggest that smoking is a modifiable risk factor in patients with aggressive prostate cancer.

An introduction to acinar pressures in BPH and prostate cancer

Intra-acinar and peri-acinar pressures in the prostate might be key factors in the evolution of its zonal morphology and the pathogenesis of BPH and cancer. Herein, I hypothesize that intra-acinar pressures lead to a decrease in apoptosis by distending or stretching acinar epithelium and its surrounding stroma. Increased prostatic smooth muscle content and tone might generate peri-acinar pressures, which could, in the long-term, counteract intra-acinar pressures and decrease epithelial stretch. Thus, it is proposed that BPH (characterized by increased prostatic smooth muscle and, therefore, raised peri-acinar pressures) might decrease the risk of prostate cancer progression by counteracting intra-acinar pressures. In the context of this theory, the transition zone might have evolved as a specialized region within the prostate that can mount a concerted stromal-epithelial response to increased urethral and intra-acinar pressures (BPH), and the urethral angulation, anterior stroma and the prostatic capsule have an adjunctive evolutionary role in this phenomenon.

Association between lncrna PCGEM1 polymorphisms and prostate cancer risk

BACKGROUND

Prostate cancer (PCa) gene expression marker 1 (PCGEM1), a long noncoding RNA, has drawn increasing attention for its important role in PCa. However, the association between genetic variations in the PCGEM1 gene and risk of PCa has not been investigated yet.

METHODS

We investigated the effect of two tagging single-nucleotide polymorphism (tSNPs; rs6434568 and rs16834898) in PCGEM1 gene on PCa risk in the Chinese men. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association.

RESULTS

We found a significantly decreased risk of PCa for rs6434568 AC and AC/AA genotype (adjusted OR=0.76, 95% CI=0.60-0.97 for AC; adjusted OR=0.76, 95% CI=0.61-0.96 for AC/AA), as well as rs16834898 AC and AC/CC genotype (adjusted OR=0.76, 95% CI=0.59-0.97 for AC; adjusted OR=0.79, 95% CI=0.62-0.99 for AC/CC), compared with the CC and AA genotypes, respectively. When we evaluated these two tSNPs together based on the risk alleles (that is, rs6434568 C and rs16834898 A), we found that the combined genotypes with four risk alleles were associated with an increased risk of PCa compared with those carrying 0-3 risk alleles (1.53, 1.19-1.97), and this increased risk was more pronounced among subjects of≤70 years (1.80, 1.24-2.62), Gleason score≥7 (1.68, 1.28-2.22) and PSA level≥20 (1.64, 1.24-2.18).

CONCLUSIONS

Our results indicated that PCGEM1 polymorphisms may contribute to PCa risk in Chinese men. Additional functional analyses are required to detect the detailed mechanism underlying the observed association.